Milling tool holder

ABSTRACT

A millin tool holder includes a tool holder body having a tool shank opening. The tool shank has an annular shoulder seated on a shoulder on the tool holder. A pair of confronting slots form an opening for receiving a pin which prevents the tool head from rotating with respect to the body.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention is related to a two-part milling tool holder whichincludes a body adapted to be mounted on a milling tool base. Areplaceable head for supporting a pair of indexable inserts has a shankreceived in an opening in the body. The head can be replaced withanother head of the same or a different style.

Milling tool inserts are commonly mounted on the end of an elongatedtool holder. It is desirable in some cutting situations to use one typeof insert for heavy milling and then another insert for cutting a radiusor the like. Occasionally, the cutter head becomes damaged or worn.Commercially available heads generally must either be scrapped orrepaired. Most of the expense in making the holder is in the body of theholder. Further, replacing a complete toll holder is time consuming.

Prior art related to tool holders such as for milling inserts may befound in my U.S. Pat. Nos. 5,468,102 issued Nov. 21, 1995 for “MillingTool Holder”; and 6,299,394 issued Oct. 9, 2001 for “Milling ToolHolder”.

The broad purpose of the present invention is to provide an improvedmilling tool holder of the type in which a body adapted to be supportedon a milling machine base, is connected to a head that supports a pairof indexable inserts. The head has a shank received in a bore in thebody.

A pair of threaded fasteners mounted on the body have their inner endsengaging the shank to cam a shoulder on the head toward a shoulder onthe body.

The arrangement is such that the user can readily exchange the headwhenever it has become damaged, worn, or needs to be exchanged toaccommodate a head having a different cutting configuration.

Although the fasteners prevent the shank from rotating with respect tothe body, my prior patent disclosed additional means for preventing suchrotation. My U.S. Pat. No. 5,468,102 used a pin in the shank-receivinghole, which was received in the slot in the end of the shank when it wasinserted in the hole.

The present invention discloses an arrangement that accommodates aheavier torque required by high speed machines for a heavier cut. Inthis case, the body has a shoulder around the shank-receiving hole. Thetool has a shoulder around the shank that seats on the shoulder on thebody. One of the channels has a pair of channels aligned along an axisthat passes through. the center of the shank-receiving hole. The othershoulder has a pair channels so that the two shoulders combine to form apair of cylindrical openings.

A cylindrical pin or key is mounted in each cylindrical opening. Eachpin is attached to a channel in one of the shoulders.

When the tool shoulder is mounted on the body shoulder in face-to-facecontact, the pins prevent the tool from rotating with respect to thebody, and increase the torque transmitting properties of the toolholder. This provides a safety feature in the event that the twothreaded fasteners should fail to prevent the tool from rotating withrespect to the body.

A single pin embodiment is also disclosed. Each shoulder has a singlechannel. When the head is mounted on the body, the pin attached to oneof the shoulders is received in the channel in the other shoulder. Thisarrangement ensures that the fastener openings in the body are alignedwith the openings in the shank.

Still further objects and advantages of the invention will becomereadily apparent to those skilled in the art to which the inventionpertains upon reference to the following detailed description of thedrawings.

DESCRIPTION OF THE DRAWINGS

The description refers to the accompanying drawings in which likereference characters refer to like parts throughout the several views,and in which:

FIG. 1 is a longitudinal view of a milling tool holder illustrating thepreferred embodiment of the invention;

FIG. 2 is a view similar to FIG. 1, but in which the body is partiallyshown in section;

FIG. 3 is a view similar to FIG. 2, but in which the body has beenrotated 90 degrees and the shank is shown partially in section;

FIG. 4 is an enlarged view showing the manner in which the fasteners amthe shank toward its fully-seated position;

FIG. 5 is an enlarged sectional view as seen along lines 5—5 of FIG. 3;

FIG. 6 is a view as seen along lines 6—6 of FIG. 3;

FIG. 7 is an end view of one of the pins;

FIG. 8 is an elevational view of one of the pins;

FIG. 9 is a view of a tool body showing the shoulder of an embodiment ofthe invention using only a single pin;

FIG. 10 is a sectional view as seen along lines 10—10 of FIG. 9;

FIG. 11 is a view of a tool shank that may be received in the tool bodyof FIGS. 9 and 10;

FIG. 12 is a view in which the tool of FIG. 11 has been rotated 90°; and

FIG. 13 is a view as seen from the right end of FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, a preferred tool holder comprises anelongated steel body 10 and an elongated steel tool head 12. The body isadapted to be mounted in the conventional manner on a milling machinebase. Body 10 has a cylindrical inner end 14 and a tapered outer end 16.The body has an outer annular shoulder 18 formed around the opening ofan internal shank-receiving bore 20. Bore 20 has a cylindrical innersurface formed about a longitudinal axis 22 which also corresponds withthe longitudinal axis of both body 10 and head 12.

For illustrative purposes, bore 20 has a depth of about 2″, slightlyless than one-half the overall length of body 10, which has a length ofabout 4.25″.

Bore 20 has a diameter of about {fraction (3/16)}″.

The body has a pair of fastener-receiving threaded openings 28 and 30.The two openings are formed about parallel axes 32 and 34 which aredisposed at right angles to and intersect longitudinal axis 22. Openings28 and 30 are longitudinally spaced about ⅜″.

Head 12 has an enlarged slotted outer end 36 for mounting indexableinserts 42 and 44. Each insert is releasably fastened to the head by afastener means 46. The inserts are relatively flat, with cutting edges50 and 52, respectively. The axes of fastener-receiving openings 28 and30 are disposed perpendicular to the planes of the inserts.

Head 12 has an annular seat 54, and an elongated cylindrical shank 56,received in bore 20. Shank 56 has a length less than the depth of bore20, and a diameter forming a snug sliding fit in the bore.

The shank has a pair of counter-drilled openings or recesses 60 and 62which are slightly longitudinally offset from fastener-receivingopenings 28 and 30, respectively, when the shank has been fully receivedin bore 20. A socket head fastener 64 is threadably received in opening28, and a second socket head fastener 66 is threadably received infastener opening 30.

The two counter-drilled openings are identical except with respect totheir location along the shank. Openings 28 and 30 are located onopposite sides of the shank. A typical counter-drilled opening and itsfastener is illustrated in FIG. 4. Counter-drilled opening 60 has aconcave, frusto-conical surface 68 adjacent the inner end of fasteneropening 28. Axis 70 of counter-drilled hole 60 is offset from axis 72 ofopening 28. This distance is somewhat exaggerated in FIG. 4 to show thatthe axis of each counter-drilled opening is closer to shoulder 18 of thebody than the axis of the corresponding fastener-receiving opening.

Fastener 64 has a rounded inner end 76 that slidably engagesfrusta-conical surface 68. As fastener 64 is threadably inserted intoopening 28, inner end 76 engages surface 68 to cam the shank toward thebottom end of the bore, thereby causing shoulder 54 to tightly abutshoulder 18.

Similarly, the rounded inner end of fastener 66 slidably engages thefrusto-conical surface of counter drilled opening 62 to cam the shanktoward the bottom end of the bore.

The diameter of the shank very snugly fits the internal surface of bore20, and shoulder 54 tightly abuts shoulder 18 to locate the inserts in aproper cutting position when the head is replaced with a different pairof inserts.

Referring to FIGS. 5 and 6, shoulder 54 of the tool head has a pair ofaligned semi-cylindrical channels 80 and 82 on opposite sides of theshank, and aligned to intersect the axis of the shank and of bore 20.Similarly, referring to FIG. 6, the body has a pair of semi-cylindricalopenings 84 and 86 formed along an axis 88 that intersects axis 22 ofthe shank. Channels 84 and 86 are also semi-cylindrical and mate withthe corresponding channels on the body when shank 56 is inserted in theshank-receiving opening 20. Axis 88 of the channels is disposed at rightangles to a plane containing the shank axis and the axis of threadedopenings 28 and 30.

A pair of cylindrical pins (keys) 90 and 92 are received in the opposedchannels of the two shoulders. Referring to FIG. 7 and 8, a typical pin90 has a outer cylindrical diameter that snugly fits in the two opposedchannels in the shoulders of the tool body and the shank. When the toolhead is mounted on the body with the shank fully received in theshank-receiving opening, as viewed in FIG. 3, the channels tightlyembrace the two pins thereby preventing relative rotation between theshank and the body, and permitting the tool to transmit a heavier torqueon a high speed machine.

To assemble the tool holder, the inserts are mounted in the usual manneron the outer end of the head. The shank is inserted in bore 20 until thechannels mate with the pins (keys) 90 and 92. Preferably, each pin isattached to a channel in either the body or the tool head as by tackwelding at 94, as viewed in FIG. 3.

Threaded fasteners 64 and 66 are then screwed into their respectivecounter-drilled openings to cam the shank until shoulder 54 abutsshoulder 18.

The process is reversed, to remove the head.

FIGS. 9-11 illustrate another embodiment of the invention in which theprimed numbers refer to similar numbers of FIGS. 1-8. Body 10′ has abore 20′. The body has an annular shoulder 54′ formed about axis 22′.Head 12′ has a shank 56′ which is receivable in shank-receiving opening20′ in the tool body.

The body has an annular shoulder 18′ formed around shank-receivingopening 20′. The head has an annular opening 54′ around shank 56′, whichseats on shoulder 18′ when the shank is received in the shank-receivingopening.

The body has a pair of threaded fastener-receiving openings 28′ and 30′.The two openings are formed about parallel axes 32′ and 34′ which aredisposed at right angles to and intersect longitudinal axis 22′. Theshank has a pair of counter drilled openings or recesses 60′ and 62′which are slightly offset longitudinally from fastener receiving opening28′ and 30′ when the shank is fully received in the bore. A pair ofsocket head fasteners (not shown) are threadably received in openings28′ and 30′ in the manner described with reference to the embodiment ofFIGS. 1-8.

In this embodiment, shoulder 18′ has a single semi-cylindrical channel82′ formed along an axis that intersects the axis of the shank, as shownin FIG. 9. Similarly, the body has a single semi-cylindrical channel 86′which is aligned with channel 82′ when the shank is received in theshank-receiving bore and the threaded openings 28′ and 30′ are alignedwith respective countersunk openings 60′ and 62′.

A pin 90′ is press-fitted into channel 86′ and then tack welded inplace. When the shank is received in the bore, the pin as seen in FIG.10, is aligned along an axis disposed at right angles to threadedopenings 28′ and 30′. When the shank is received in the shank-receivingopening, the shoulders of the tool body and the tool holder will onlyabut one another when the pin is received in channel 82′. Thisarrangement ensures that the fastener-receiving opening in the body isaligned with the counter drilled opening in the shank.

Having described my invention, I claim:
 1. A tool holder assembly,comprising: an elongated tool holder body having a longitudinal axis, anend shoulder and an elongated shank-receiving bore extending from saidend shoulder along said longitudinal axis; a tool holder head adapted tosupport at least one cutting insert, said tool holder head having acylindrical shank slidably receivable in said shank-receiving bore, andan annular shoulder axially alignable with said end shoulder; means forbiasing said tool holder head along said longitudinal axis so that saidannular shoulder has pressure engagement with said end shoulder on thetool holder body; said biasing means comprising at least two threadedopenings in said tool holder body extending normal to said longitudinalaxis in a common plane containing said longitudinal axis; said threadedopenings being equi-angularly spaced apart in the circumferentialdirection, said threaded openings also being spaced in the axialdirection so that said openings communicate with said bore at axiallyspaced points therealong; said shank having at least two frusto-conicalrecesses adapted to register with said threaded openings when said shankis inserted into said bore; a threaded fastener threaded into each ofsaid threaded openings to penetrate a respective frusto-conical recess,whereby said tool holder head is biased along said longitudinal axis;means for transmitting torque between said tool holder head and saidtool holder body when said shank is slidably inserted into the borecomprising: the tool holder head annular shoulder having a first channelhaving a semi-cylindrical configuration formed alone an axis whichintersects and is at right angles to said longitudinal axis, the toolholder body having a second channel opposing the first channel andformed along an axis which intersects said longitudinal axis; and a keydisposed in said fist channel and said second channel to preventrotation of the tool holder head with respect to the tool holder bodyabout said longitudinal axis.
 2. A tool holder assembly as defined inclaim 1, in which the key has a cylindrical configuration.
 3. A toolholder assembly as defined in claim 1, in which the key is attached toone of said channels so as to be fixed thereto.
 4. A method for forminga tool holder assembly, comprising the steps of: forming an elongatedtool holder body having a longitudinal axis, an end shoulder and anelongated shank-receiving bore extending from said end shoulder alongsaid longitudinal axis; forming a tool holder head adapted to support atleast one cutting insert: said tool holder head having a cylindricalshank slidably receivable in said shank-receiving bore, and an annularshoulder axially alignable with said end shoulder; biasing said toolholder head along said longitudinal axis so that said annular shoulderhas pressure engagement with said end shoulder on the tool holder bodyby using at least two threaded openings in said tool holder bodyextending normal to said longitudinal axis in a common plane containingsaid longitudinal axis; spacing said threaded openings equi-angularyapart in the circumferential direction, spacing said threaded openingsin the axial direction so that said threaded openings communicate withsaid bore at axially spaced points therealong; registering twofrusto-conical recesses in said shank with said threaded openings whensaid shank is inserted into said bore; threading a fastener into each ofsaid threaded openings to penetrate a respective frusto-conical recess,whereby said tool holder head is biased along said longitudinal axis;transmitting rotational motion between said tool holder head and saidtool holder body when said shank is slidably inserted into the bore byforming a first channel in the tool holder head annular shoulder alongan axis which intersects and is at right angles to said longitudinalaxis; forming a second channel in the tool holder body end shoulderopposing the first channel in the tool holder head annular shoulderalone an axis which intersects and is at right angles to saidlongitudinal axis; disposing a key in said first and second channels toprevent rotation of the tool holder head with rest to the tool holderbody about said longitudinal axis as the tool holder body is beingrotated about said longitudinal axis, forming a first companion channelin said tool holder head annular shoulder along an axis which intersectsand is at right angles to said longitudinal axis; forming a secondcompanion channel in the tool holder body end shoulder opposing thefirst companion channel along an axis which intersects and is at rightangles to said longitudinal axis; and disposing a second key in saidfirst and second companion channels to prevent rotation of the toolholder head with respect to the tool holder body about said longitudinalaxis.
 5. A tool holder assembly, comprising: an elongated tool holderbody having a longitudinal axis, an and shoulder and an elongatedshank-receiving bore extending from said end shoulder along saidlongitudinal axis; a tool holder head adapted to support at least onecutting insert, said tool holder head having a cylindrical shankslidably receivable in said shank-receiving bore, and an annularshoulder axially alignable with said end shoulder; means for biasingsaid tool holder head along said longitudinal axis so that said annularshoulder has pressure engagement with said end shoulder on the toolholder body; said biasing means comprising two threaded openings in saidtool holder body extending normal to said longitudinal axis in a commonplane containing said longitudinal axis; said threaded openings beingspaced about one hundred eighty degrees apart in the circumferentialdirection, said threaded openings also being spaced in the axialdirection so that said openings communicate with said bore at axiallyspaced points therealong; said shank having two frusto-conical recessesadapted to register with said threaded openings when said shank isinserted into said bore; a threaded fastener threaded into each of saidthreaded openings to penetrate a respective frusto-conical recess,whereby said tool holder head is biased along said longitudinal axis;means for transmitting torque between said tool holder head and saidtool holder body when said shank is slidably inserted into the borecomprising: the tool holder annular shoulder having a first channel; thetool holder body having a second channel opposing the first channel; akey disposed in said first and second channels to prevent rotation ofthe tool holder head with the tool holder body about said longitudinalaxis; and the tool holder annular shoulder having a first companionchannel therein, the first companion channel having a semi-cylindricalconfiguration formed along an axis that is aligned with the firstchannel of the tool holder head annular shoulder, and which intersectsthe longitudinal axis of said body, and the tool holder body having asecond companion channel aligned with the second channel of the toolholder body, on opposite sides of the shank-receiving opening, andformed along an axis which intersects and is at right angles to saidlongitudinal axis openings.
 6. A tool holder assembly as defined inclaim 5, in which the first companion channel opposes the secondcompanion channel when the shank is inserted into said bore, andincluding a second key disposed in said first companion channel and saidsecond companion channel to prevent rotation of the tool holder headwith respect to the tool holder body about said longitudinal axis.